Rec 2' trailer: Horror sequels you couldn't watch, even if you wanted to?

The red band trailer for the sequel to one of the self-proclaimed scariest movies of all time literally dares you to watch it. I'm a wimp, so there's no way I'm actually going to watch a heavily-armed SWAT team and a government official enter a quarantined apartment building to try to contain a virus that has turned the occupants into mindlessly violent, raging beasts a demonic nightmare of biblical proportions more terrifying than they could have possibly imagined. But it did get me wondering if a horror film has ever frightened you so badly, you couldn't watch the sequel even if you wanted to. So this isn't like, I've never seen a single Nightmare on Elm Street,Â this is I saw the original Nightmare on Elm Street, and haven't seen a Freddy Krueger film since.Â Can a horror movie be too effective?